# The kinetic energy of the body at the moment of throwing it vertically upwards

**The kinetic energy of the body at the moment of throwing it vertically upwards is 400 J. Determine to what height the body can rise if its mass is 2 kg.**

Ek1 = 400 J.

g = 10 m / s2.

m = 2 kg.

h2 -?

If the air resistance during the movement of the body is neglected, then the law of conservation of total mechanical energy is valid for it. The sum of the potential and kinetic energy of the body does not change, but passes from one type to another: Ek1 + En1 = Ek2 + En2.

The potential and kinetic energy of a body is determined by the formulas: Ek = m * V ^ 2/2, En = m * g * h.

We will assume that the body is thrown from the surface of the earth, which means h1 = 0 m, En1 = 0 J.

At the highest point of the body’s ascent, it stops V2 = 0 m / s, Ek2 = 0 J.

Ek1 = m * g * h2.

h2 = Ek1 / m * g.

h2 = 400 J / 2 kg * 10 m / s2 = 20 m.

Answer: the body can rise to a height of h2 = 20 m.